o2 sim controversy concerning a/f mixture

[firebirdrumble00]

Alot of people i've noticed want to buy o2 sims. I don't understand this b.c. to the best of my knowledge i know that it is the o2 sensors job to measure the exhaust gas coming out of the exhaust manifold and then accordingly richen or lean out the mixture in an attempt to get the air/fuel mixture as close to stoich (14.7) in order to achieve a perfect burn in the cylinder.

If you guys get o2 sims then the computer will think that the exhaust gases are already perfect air/fuel mixes and thus not give perfect readings or adjustments.

Please input your thoughts on this I would gladly appreciate it! Thanks in advance.

[mrbako]

O2 simulators are used post cat....

that o2 sensor is there to measure the cat efficiency and not to adjust the fuel trim.

the two o2's that do that task are located in the exhaust manifolds.

hope that clears up the question...please ask more questions if i didn't do a good enough job explaining it.

[tdaddyz]

mrbakos right, people use them when they run no cat, gutted cat, or a cat so highflo it throughs a code

[firebirdrumble00]

Oh so your saying that we have 3 o2's and one is used to measure cat effeciency and that is the only one that is replaced with an o2 sim. Okay I didnt know that but I see what your saying. Thanks for the clarification!

[mrbako]

actually 4 on some models...i think there's one right before the cat on some models as well.